crankshaft not turning smoothly

[notmytarga]

I am evaluating a 911/44 California 1975 2.7 L engine that I bought as a possible temporary replacement while I rebuild my matching engine with a blown piston/exhaust valve.

I have no history on the engine. It's appearance would suggest it might not have been running well when removed.

Clues - CIS box is open with injectors out of the manifold - essentially unsalvageable. Left timing cover has lots of gasket sealant used. Pressure fed tensioners are there but the oil lines are missing. Valve covers - lowers are missing (including two adjoining studs on one side), uppers are just set on - no nuts. Upper valve covers and fan painted blue. Distributor - missing cap and rotor. No plugs or wires. Wiring harness is mangled, including the 14 pt connector missing with just 14 wires with contacts.

My plan is to use parts from my own engine to replace any missing parts - such as plug wires , distributor cap, whole CIS system, wiring harness, etc.

The engine turns with fan nut wrenching but seems to stop and need some belt squeezing at one consistent point (near #5 TDC). I backed off all the valve adjustments to reduce valve spring effects and there wasn't any change. Looking through the spark plug hole tells me that the pistons are all intact and moving.

So the question is - What can cause this "binding" and should I proceed with outfitting this engine as a temporary replacement? Any recommendations for further inspection?

Please give me your input.

[Steve@Rennsport]

Like all emissions-equipped 2.7's, these things ran pretty hot and the mag case warps over time. When this happens, the main bearing saddles are not perfectly lined up and the crank becomes difficult to rotate. This happens everytime a mag-cased engine is taken apart.

The only cure is to disassemble the whole thing and have the case halves machined flat and the main bearing saddles bored back to standard. That,...makes a nice bottom end to build a good 2.7.

[notmytarga]

Thanks Steve!

The 2.7 Mag case engine in the car with the blown piston luckily turns pretty smoothly all around.

Will this 'donor' engine start and run for a few months while I rebuild the original engine?? The engine did have the thermal reactors removed and the airpump is missing (like mine).

If it is a warped case and the crank is binding wouldn't it bind every rotation rather than at #5 TDC (2 rotations)? Is it the intermediate shaft then?

With case warpage in mind I will turn it around again and make sure my observation is accurate.

[efhughes3]

Originally Posted by notmytarga

Will this 'donor' engine start and run for a few months while I rebuild the original engine?? The engine did have the thermal reactors removed and the airpump is missing (like mine).

Wow, that is a lot of question to ask over the internet! Steve will need to get his Ouija board out to answer that one.....

[Steve@Rennsport]

Originally Posted by notmytarga

Thanks Steve!

The 2.7 Mag case engine in the car with the blown piston luckily turns pretty smoothly all around.

Will this 'donor' engine start and run for a few months while I rebuild the original engine?? The engine did have the thermal reactors removed and the airpump is missing (like mine).

If it is a warped case and the crank is binding wouldn't it bind every roatation rather than at #5 TDC (2 rotations)? Is it the intermediate shaft then?

With case warpage in mind I will turn it around again and make sure my observation is accurate.

Depending on all the details of the blown 2.7, its may be a better candidate for refurbishing right now.

A "tight" engine will experience very high oil temps and can ruin the case and crank if you run it. If it seizes, its junk,...............
You might have a failed rod bearing or an intermediate shaft/bearing problem. I would NOT run that one until its repaired.

[Eagledriver]

You might have some carbon built up in the number 5 cylinder that is causing your binding. When the engine sits for awhile in a humid environment some of the carbon can fall off the piston and head. It will collect in the bottom of the cylinder and could cause your binding. You have no history on this motor so there is no way to know if it will run and if it does for how long. I'd give it a try by putting on the stuff from your motor and see how it runs. If it doesn't run well you'll only be out the hours you spent putting it in.

-Andy

[notmytarga]

I'm continuing moving equipment to the "found" engine (on the engine stand in the pictures). As I did a valve adjust I noted that indeed the crank is binding at 5 AND also opposite it - so the case is warped or the crank is possibly bent. I did note that as I turned the engine over a few times that the tightness improved.




This engine has not seen oil in a while and when I inverted it to remove the air injectors water flowed out of the front oil sensor - about a pint I'd say. The sump screen was pretty grimey too. It will be a treat if this thing will fire up. I'll have to resist the temptation to work too hard to get it running. I'm preparing myself for failure by telling myself; it is a cheap mistake to try, practice manipulating things like the air injectors and oil lines and when the "found" engine is tucked in the back, an nice storage place for spare parts and my CIS system.



I had a dickens of a time getting the air injectors out despite two days of penetrant and tapping. Broke 1,3,5 & 6 off - I extracted #1, plugged #3 with a broken extractor tip and couldn't budge # 5 & 6. Good practice for my "real" engine teardown.

I'm enjoying my first engine-stand valve adjust and playing with the backside Go - No Go method to check - What I found is that I have been a little too confident in my valve adjusts - I started doing them 20 years ago on a VW. Mine are uniform but I can pass a 0.003 at the cam- too loose. Has anyone seen a 0.0025/0.003 Go/NoGO feeler? That would be ideal. A nice advantage of the backside method is that you can check all your valves with only half the covers off.

[efhughes3]

Man, I don't know if I'd waste any effort on that engine.....why not concentrate effort on your real motor?

Why would you second guess the traditional valve adjust method @ .004" under the Elephant's foot by focusing on the backside check as being the final say on whether yours are correct? I'm still not sold on the accuracy of the backside method, and it seems to be a shortcut for a "real" valve adjust. I'm sure it gets you close, but it is hard to argue a .004" feeler as opposed to whether one or the other feelers goes in behind.

[notmytarga]

I agree that it is likely a waste of time - but it will be a bonus if I can take more time on the rebuild if have the 911 on the street again. It will also let me know more about the condition of the "unreal" engine.

The standard 0.004" technique is fine if you can calibrate your blade feel. My 0.006" blade's markings are nearly worn off from all the VW valve adjustments I did on my '67 but it turns out that I was too loose on all but two valves I did on this engine on the stand with no tin in the way. Now that I have recalibrated myself I know I can be better - the 0.004" blade needs to have a real snug drag, I had always gone for a smooth drag. I found the fastest way was to check it with the backside and then confirm at the elephant foot - the feel on the blade was uniform once I did this. I now can trust myself more.

[efhughes3]

That makes sense, using the backside as a calibration for your feel on the frontside. I suppose I opted for a lighter drag when I did my first couple of adjusts, now, I think I've got the feel. And, I've got island911's valve adjust tool, which is about 8 times better than the regular feeler gauge, IMO.

[cgarr]

If you run them down with your fingers til they stop then back them off 1/8th of a turn you will be real close, these are 1mm pitch threads, 1/8 turn is .005

[efhughes3]

Originally Posted by cgarr

If you run them down with your fingers til they stop then back them off 1/8th of a turn you will be real close, these are 1mm pitch threads, 1/8 turn is .005

Even less precise......what is wrong with using a .004" feeler???!!!

It seems like there is a quest for the "free lunch" when it comes to valve adjustments......what's so hard about doing it correctly??

[cgarr]

Originally Posted by efhughes3

Even less precise......what is wrong with using a .004" feeler???!!!

It seems like there is a quest for the "free lunch" when it comes to valve adjustments......what's so hard about doing it correctly??

So how much drag on the gauge to call it good? I know for a fact that each full turn of the screw is .03937 exactly! What do you know, thats just how a micrometer works.

[efhughes3]

Originally Posted by cgarr

So how much drag on the gauge to call it good? I know for a fact that each full turn of the screw is .03937 exactly! What do you know, thats just how a micrometer works.

I'll take my chances with my "feel" on the drag, rather than trying to guess what 1/8 of a turn looks or feels like. Plus, when I cinch the locknut on the adjuster down, I still have my feeler in, so I get instant gratification on whether the adjuster turned a hair or not by the drage when I pull the gauge out. You won't get that feeling of surety with the "1/8 turn" method.

[efhughes3]

Here's my feeler gauge that I absolutely love! Just did my 500 mile adjust yesterday. After getting the valve covers off, It couldn't have taken more than 30-45 minutes to do the actual adjustment.

[notmytarga]

Okay - so the valve adjust is behind me now... I like the Island tool too. I was sporting four to do the check. My oldest at 0.003, the standard 0.004, the Island 0.004, and a new one to get the 0.0025 for the Go on the Backside. It's nice to have a each of the Go and No Go separate too.

An update for those interested in what happened with the "rescued" engine.

I installed this trashed engine and, after donating my distributor as well, it fired up! Unfortunately lots of blue smoke, about the same as my 'real' engine with the hole in the piston. I'm not sure if it is valve guides or rings or even something else. I took a quick drive to warm it up and felt like a Blue Angel with "Smoke On".

It seems to like the feeling of oil flowing after probably many years and turns fairly easily without much halting at #3/5 as it did initially, even with plugs in.

There is a shuddering that makes me think there is a balance problem rather than a cylinder or two not firing. My failed attempt to fully remove the air injectors as well as a broken exhaust stud and maybe a cracked 3 into1 thermal reactor replacement seems to have resulted in some exhaust leak sound - but it is a very noisy engine overall.

There is a fair bit of smoke coming from the engine itself which makes me think that it might need to burn off the penetrants, old oil and cleaners I used. Maybe a long ride at night in the boonies. It looks like the engine will serve as an emergency transportation resource and storage place for my engine externals while the "real" engine is being torn down.

The good news is that all the air injectors on the 'real' engine came out without complaint. This makes me feel that my 54K mile engine is in much better shape. Exhaust came off after #1-3 inboard studs snapped and for all but one of the others the stud backed out. Is that normal? I'm getting the impression that the Left bank was running hotter than the Right. Same with the stainless bolts I used five years ago between the 3 into 1 manifold and the heat exchangers - Two of the three on the left were cooked on and broke the bolt, none on the right. Could this be from unburned fuel from the #1 piston hole getting burned in the manifold?

[notmytarga]

A long overdue update. I tore down this engine to bring some cylinders and pistons to the machinist. I only had time to get the right bank off before the planned trip to Sunnyvale to visit Ted Robinson at German Precison.

I was concerned that the pistons were not CIS which would allow me to replace my damaged P & C. A Pelican search of the numbers on them and Ted confirmed that they are RS pistons. I was disappointed that they didn't match but hopefully the whole set is usable.

I would like to confirm if these are reasonable to run with the CIS induction.



When I returned from the trip south I tore down the other bank and I think I found the explanation for the crank not turning nicely. The top of the #2 piston had dents that looked like a screw had been impacted - which would be worse when at TDC during valve overlap - which is at the #5 firing position. You can see the dents in this picture - they are at the top and bottom of the piston at the periphery.

I sent these P &C's to Ted to complete the RS set - he hasn't evaluated them yet - any guesses if they are usable?



Please offer your opinions on the suitability of these RS pistons with CIS.

[Steve@Rennsport]

RS pistons on a CIS-injected car have some drivability issues caused by lean spots in the combustion chambers.

The RS piston crowns do not have that bump on the intake side that promotes swirl for an evenly distributed air/fuel mixture in the cylinder, particularly at less than WOT. It will run, but not all that well.

[notmytarga]

Thanks Steve. What is WOT?

So what to do?

Use the RS with CIS and deal with poor performance.

Build with the RS and change to another induction system.

Purchase new P & C's for the CIS.

Purchase JE pistons. Use 6 of the used cylinders.

What cam changes might I need?

Apparently I have some difficult and expensive decisions to make.

[kenikh]

WOT = Wide Open Throttle

CIS = Keep It Stock (C sounds like K right? )

Are your cylinders Alusil or Nikasil - big difference on reusability